Stormwater Water Quality Treatment Options Alvin Shoblom, P.E. Hydraulics Engineer.
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Transcript of Stormwater Water Quality Treatment Options Alvin Shoblom, P.E. Hydraulics Engineer.
Stormwater Water Quality Treatment Options
Alvin Shoblom, P.E.Hydraulics Engineer
Options
Low Impact Development (LIDs) Engineered
Low Impact Development (LIDs)
Definition:
LID is the concept of designing projects to minimize the effect of natural hydrology and water quality.
This is primarily accomplished by minimizing impervious surface area and providing opportunities for filtration of stormwater by vegetation and infiltration into the soil.
For highway projects, LID refers to the treatment of highway runoff within the linear highway right of way using techniques and facilities that generally require minimal hydraulic engineering.
LID Options
Minimizing impervious area Preserving or restoring adjacent roadside
landscaping Mimicking natural drainage patterns (e.g. using
sheet flow, dispersion, infiltration, and existing open channels)
Incorporating/retrofitting vegetated shoulders and drainage channels with soil amendments
Soil Amendment
Example of maintaining existing vegetated shoulder (sheet flow)
Engineered Treatment Facilities
Stormwater Ponds Biofiltration Swales Filter Strips Bioslopes Proprietary Structures
Bioretention Pond
Bioretention Pond
Bioretention Pond
Bioretention Pond Sizing Example
Given: Salem Oregon Project Contributing ODOT impervious area (CIA) for
project is 1 acre
Determine: Water Quality Design Storm to size the pond.
The design storm is a percentage of the 2-year, 24 hour event for the project site.
Bioretention Pond Sizing Example (Cont.)
Results: Volume calculated is 3755 cubic feet using
an appropriate hydrology method. Therefore, the volume in the pond would
need to be 3755 cubic feet or greater.
Bioretention Pond
Biofiltration Swale
(with soil amendment)
Biofiltration Swale
Filter
Strip
Filter Strip
Bioslope
Bioslope
Downstream Defender
(Separation unit)
Stormwater Management Stormfilter
(Filtration unit)
Treatment Solution SelectionFor project with identified water
Issues and treatment goals
Incorporate LID techniques suchas soil amendments, impervious
surface reduction, preservingor restoring adjacent roadway landscaping
Submit hydraulic Design Deviation for other BMP
not listed in WaterQuality Guidance/Tech Bulletin with supporting
documentation
Select appropriatetreatment based on:
• BMP removal capabilities• Constructability• Cost and maintenance• Site constraints (steep Slopes, high groundwater, Bedrock, etc)
Go to StormwaterManagement Tech
Bulletin and attachedWater Quality Guidance
Sufficient LIDs Incorporated?
Water Quality SelectionComplete
YN
BMP selected from Recommended listFrom Water Quality
Guidance/Tech Bulletin?
N
Y
LIDs and/or EngineeredTreatment option used
To meet treatmentgoals
Sufficient design?
Y
Re-Submit deviation for for other BMP
not listed in WaterQuality Guidance/Tech Bulletin with supporting
documentationN
Design Guidance
Stormwater Management Program Technical Bulletin Provides Selection and Design Guidance Technical Bulletin #GE09-02B Available online
Hydraulic Design Deviation Requests Directive Process for design not adhering to ODOT guidance Directive #TSB08-01(D) Available online